Extendable guidewire assembly

ABSTRACT

An extendable guidewire assembly comprising: a guidewire having a tapered proximal end; an extension wire having a tapered distal end; and a polymeric tubular sleeve reinforced with a helical coil that is fixedly attached about the tapered distal end of the extension wire such that the tapered distal end of the extension wire extends partly through the sleeve lumen, said lumen having a diameter that is smaller than the untapered diameter of the guidewire and wherein said lumen expands radially when the sleeve is under axial compression and contracts radially when the sleeve is under axial tension.

This is a continuation of Ser. No. 08/015,215 filed Feb. 9, 1993, nowabandoned, which is a continuation-in-part of Ser. No. 07/750,558 filedAug. 26, 1991, now U.S. Pat. No. 5,188,621.

TECHNICAL FIELD

This invention is in the general field of surgical instruments andrelates specifically to an extendable guidewire assembly that is used incardiovascular and endovascular procedures to facilitate the placementof catheters within the vasculature of patients.

BACKGROUND

The general procedure for placing catheters within vessels is to track aguidewire through the vessel to the desired position and advance thecatheter over the guidewire. Guidewires are required because thecatheters themselves do not have sufficient column strength ortorqueability to be able to be tracked or steered through the vessel.See, for instance, U.S. Pat. No. 4,884,579.

In some procedures such as angioplasty using dilatation ballooncatheters, it is necessary to exchange catheters to increase balloonsize. It may also be necessary in some instances to replace cathetersdue to material fatigue. Two guidewire techniques have been employed insuch instances. In one, the initial guidewire is removed and replacedwith an exchange wire that is somewhat greater than double the length ofthe catheter. In order to avoid the need for a separate exchange wire asecond technique that involves attaching an extension wire to theinitial guidewire was developed.

U.S. Pats. Nos. 4,917,103 and 4,922,923 describe an extendable guidewireassembly that employs a sleeve that is connected to the proximal end ofthe guidewire and into which the distal end of the extension wire isinserted. The sleeve and extension are then crimped to form a permanentjoint or union between the two wires.

U.S. Pat. No. 4,875,489 describes another type of extendable guidewireassembly in which one of the wires has a tapered tip and the other hasan expandable sleeve into which the tip is received. A second concentricsleeve encloses the expandable sleeve to ensure a friction fit betweenthe tapered tip and expandable sleeve.

U.S. Pat. No. 4,966,163 describes yet another kind of extendableguidewire assembly. In this assembly one of the wires carries aninternally threaded sleeve and the other wire carries a threaded head,The two wires are coupled together by threading the head into thesleeve.

U.S. patent application Ser. No. 688,915, filed 19 Apr. 1991, describesan extendable guidewire assembly in which the ends of the guidewire andextension wire carry axial interlocking members and the extension wirecarries a retractable sleeve which encloses the interlocked members.

Applicant is also aware of an extendable guidewire assembly design inwhich one of the wires carries an open-ended sleeve and the other wirehas a tapered tip encircled by a helical coil. The wires are coupled byinserting the tip into the sleeve and twisting it. The twisting causesthe coil to expand and form a friction fit with the interior of thesleeve. The wires are uncoupled by twisting the tapered tip wire in thereverse direction.

U.S. patent application Ser. No. 07/983,478 filed 1 Dec. 1992 describesan extendable guidewire assembly. A first polymeric sleeve allows forthe connection of the guidewire and the extension wire and a secondpolymeric sleeve acts as a guide to focus the guidewire into the firstpolymeric sleeve. The application also describes a kit for use inconnecting and disconnecting the guidewire assembly. The kit includesthe guidewire, the extension wire, the first and second polymericsleeves and a detachment tool.

A primary object of the present invention is to provide an extendableguidewire assembly with a guidewire and extension wire that can beeasily connected and disconnected and that will not kink at the junctionof the wires.

DISCLOSURE OF THE INVENTION

The invention is an extendable guidewire assembly for use within apatient's vasculature comprising in combination:

(a) a guidewire having a distal end that is adapted to be fed into saidvasculature and a tapered proximal end;

(b) an extension wire having a proximal end and a tapered distal end;and

(c) a sleeve comprising a helical coil covered with or embedded in apolymer having first and second ends and a lumen extending therebetween,said first end being fixedly attached concentrically about one of eitherthe proximal end of the guidewire or the distal end of the extensionwire such that said one end extends partly through the lumen of thesleeve, said second end being adapted to receive the other of theproximal end of the guidewire or the distal end of the extension wire,said lumen having a diameter that is smaller than the untapered diameterof the wire to which the sleeve is not fixedly attached and wherein thelumen expands radially when the sleeve is under axial compression andcontracts radially when the sleeve is under axial tension.

In another embodiment, the invention also includes a second polymericsleeve having first and second ends and a lumen extending therebetween,said first end having a smaller inside diameter than said second end,said first end being concentric about the first polymeric sleeve, saidsecond end being adapted to receive the proximal end of the guidewire,and to guide the guidewire into the proximal end of the first polymericsleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary elevational view of a preferred embodiment ofthe extendable guidewire assembly with the guidewire and extension wirein a disconnected configuration.

FIG. 2 is a fragmentary elevational view of the embodiment of FIG. 1with the guidewire and extension wires in their connectedconfigurations.

FIG. 3 is a fragmentary elevational view of a second preferredembodiment of the extension wire of the invention with the first andsecond polymeric sleeves incorporated. The extension wire is shown in adisconnected configuration.

FIG. 4 is a fragmentary elevational view of the embodiment of FIG. 3with guidewire and extension wires in their connected configuration.

FIG. 5 is a fragmentary elevational view of the embodiment of FIG. 3with guidewire and extension wires in their connected configuration,with the second polymeric sleeve removed.

FIG. 6 is a partial side view of the first polymeric sleeve withembedded coil.

FIG. 7 is a fragmentary elevational view of the guidewire of theinvention with the first and second polymeric sleeves incorporated.

Like elements in the drawings bear the same reference numeral.

MODES FOR CARRYING OUT THE INVENTION

The drawings illustrate the preferred embodiments of the extendableguidewire assemblies of the invention. The three principal components ofthe first preferred assembly are: a guidewire 11, an extension wire 12,and a sleeve 13. In these figures only the proximal end 14 of theguidewire and the distal end 15 of the extension wire are shown. Theremainders of the two wires are not shown and are of conventionalstructure.

While this invention may be practiced with guidewires of any length anddiameter, it will typically be employed with stainless steel ornickel-titanium alloy guidewires and extensions that are ≦0.46 mm indiameter (untapered), more normally 0.25 to 0.40 mm in diameter(untapered). Preferably, the diameters of the guidewire and extensionwire are the same. In most instances the length of the guidewire will bein the range of 100-200 cm and the extension will be on the order of 125to 225 cm in length.

The proximal end 14 of guidewire 11 has a tapered section 16. Formanufacturing convenience the taper will normally be conical, althoughother taper configurations may be used. The taper is continuous and thelength of section 16 will normally be 3 to 7 cm, more usually 5 to 6 cm.

The distal end 15 of the extension wire 12 has a similarly taperedsection 17. It, too, is preferably conical, continuous and extends overa length of 3 to 7 cm, usually 5 to 6 cm.

Sleeve 13 preferably has an outer diameter that is equal to or less thanthe outer diameters of the untapered portions of the guidewire andextension wire. Correspondingly, the diameter of its lumen 18 will beless than the individual diameters (untapered) of the two wires. Thelumen diameter will typically be 0.2 to 0.36 mm, more usually 0.25 to0.30 mm. In the embodiment shown in the drawing the sleeve is attachedto the tapered end of the extension wire by means of an adhesive 19.Because the diameter of the lumen 18 is smaller than the untapereddiameter of the extension wire, the site of affixation is on the taperedportion.

The length of tubular sleeve 13 is such that the tapered portion 17 ofthe extension wire extends within the lumen over half the length of thesleeve. As shown in the drawing, when the wires are connected thetapered end of the guidewire also extends into the lumen over half thelength of the sleeve. Thus, the tapered tips of the wires axiallyoverlap within the lumen. With wires of the dimensions given above, thelength of the sleeve will usually be 5 to 8 cm, more usually 6 to 7.5cm.

The tube is made of a polymer that is reinforced with a helical coil 22that will provide a friction fit between the contact surface between itsinner wall and the tapered section 16 of the guidewire. Further, thenature of the mechanical properties of the polymer and the wallthickness of the sleeve are such that the sleeve will act as a "Chinesefinger tube" and its lumen will expand when the sleeve is under axialcompression and contract when the sleeve is under axial tension.

The helical coil 22 is preferably formed of a wire or ribbon which canbe platinum, stainless steel, or any other biocompatible material stiffenough to support the polymer. The wire or ribbon is coated with orimbedded in the polymer. The polymer may be polyimide or other polymerof like mechanical properties. The wire or ribbon imbedded in thepolymer provides a structure which prevents the kinking of the polymericsleeve 13 during attachment and handling, as well as a serrated outsidesurface for better gripping for attaching the wires together.

The guidewire and extension wire are connected by simply inserting thetapered end of the guidewire into the sleeve until a tight friction fitbetween the sleeve and the tapered end of the guidewire is achieved.(See FIG. 2.) Locking of the connection between the wires may beverified by applying axial tension to both wires close to the sleevejunction. Because of the "Chinese finger tube" fit, the wires can bedisconnected only by placing force on (gripping) the distal end face 20of the sleeve, and pulling the tapered end of the guidewire from thelumen. Any manipulation that places the sleeve under axial tensioncontracts the lumen and exerts radial force at the contact surfaces ofthe sleeve and the tapered portion of the guidewire.

In a second embodiment, the extension wire is directed into the firstpolymeric sleeve 13 by means of a second polymeric sleeve, introducer 21(See FIGS. 3 and 4). The introducer comprises a polymeric materialwherein the proximal end 23 is generally concentric about the firstpolymeric sleeve 13 described above. The distal end 25 of the introducer21 has a greater inside diameter than the proximal end 23 such that theguidewire 11 is easily inserted into the introducer (FIG. 4). Theintroducer contains a tapered section 27 that directs the wire into thefirst polymeric sleeve 13. When the guidewire 11 is securely in placeinside the first polymeric sleeve 13, the introducer is removed (FIG.5). In the embodiment shown in FIGS. 3 and 4 the introducer has a slitalong the entire length of its proximal 23 and distal 25 segments.Following insertion of the proximal end 14 of guidewire 11, theintroducer 21 is peeled away by grasping tab 29 and pulling. The slit inthe introducer is thereby opened and the introducer can easily be pulledoff of the extension wire and guidewire assembly.

The proximal end 23 of introducer 21 preferably has an inner diameterthat is smaller than the outer diameter of sleeve 13. The inner diameterof proximal end 23 will typically be 0.22 to 0.46 mm, more usually 0.28to 0.30 mm. The distal end 25 of the introducer 21 preferably has aninner diameter that is large enough for easy insertion of the guidewire11. The inner diameter will typically be 0.5 to 3.0 mm, more usually 0.6to 1.4 mm. The length of the introducer is such that the sleeve 13extends within the lumen of the introducer 21 over half the length ofthe first polymeric sleeve 13. As shown in the drawings, when the wiresare connected, the tapered end of the guidewire also extends into thelumen over half the length of the introducer. With wires of thedimensions given above, the length of the introducer will usually be 3to 10 cm, more usually 3.5 to 5 cm.

The introducer 21 is made of polymeric tubing. The material is such thatit has the mechanical strength to withstand the insertion of theguidewire, but can be easily peeled away when the insertion is complete.In this regard, the wall thickness of the introducer will usually be0.10 to 0.13 mm and the introducer will be made of 1 to 5 mm outerdiameter polyethylene tubing. The introducer may also be made of tubingof other polymers of like mechanical properties.

An extendable guidewire assembly according to the invention was made asfollows. Using a centerless grinder, the proximal end of a 195 cm longstainless steel catheter guidewire having a 0.014" OD was ground to0.002" tip OD with a 6.0 cm taper length. The end of a different wire ofthe same diameter, about 160 cm long, was ground similarly as theguidewire. This wire served as the extension wire. Polyimide tubingreinforced with a helical coil comprising a metal ribbon (purchased fromHudson International) with a 0.013" OD and a 0.001" wall thickness wascut squarely to about 7.5 cm long. The ends of the tubing were carefullysanded to remove any remaining burrs from the imbedded ribbon. A thinfilm of epoxy adhesive was applied on the ground segment of theextension wire. The tip of the extension wire was inserted into thepolyimide tubing and pressed until the wire locked. The epoxy wasallowed to cure overnight. Alternatively the epoxy may be cured byheating for 3 min at ≈135° C. Extension of the guidewire wasaccomplished by inserting the ground proximal end of the guidewire intothe polyimide spiral reinforced tube of the extension wire. The catheterwire was pressed firmly into the tubing.

Where the extension wire and guidewire assembly included an introducer,the introducer was formed from polyethylene tubing according to thefollowing procedure.

A 7.5 cm length of tubing with an outer diameter of 2 mm was cut. Heatwas applied to the proximal end 23 of the tubing in order to form asection that is 4 cm long and has an inner diameter of about 0.30 mm.The tab 29 was similarly formed by heat shrinking the section of tubingthat comprises the tab until the tubing had an outer diameter of about0.89 mm and was about 1 cm long.

In order that the introducer be removable after the guidewire has beeninserted, a slit was cut the length of the introducer. The introducerwas slid into place over the first polymeric sleeve 13 and shrunk fitover the first polymeric sleeve to secure it in place. An openingdimensioned 2 by 4 mm was cut in the distal end 25 of the introducer 21such that the proximal end 14 of guidewire 11 could easily be insertedinto the introducer.

While the above-described embodiments show the first and secondpolymeric sleeves affixed to the extension wire, it will be appreciatedthat the respective wire structures may be reversed as shown in FIG. 7(i.e., the sleeves 13 and 21 are affixed to the proximal end of theguidewire 11). Similarly, other modifications of the above-describedembodiment of the invention that are obvious to those of skill in themechanical and guidewire/catheter arts are intended to be within thescope of the following claims.

We claim:
 1. An extendable guidewire assembly for use within a patient'svasculature comprising in combination:(a) a guidewire having a distalend that is adapted to be fed into said vasculature and a taperedproximal end; (b) an extension wire having a proximal end and a tapereddistal end; and (c) a first polymeric sleeve comprising a helical coilcovered with or embedded in a polymer having first and second sleeveends and a lumen extending therebetween along an axis, said first sleeveend attachable concentrically about one of either the proximal end ofthe guidewire or the distal end of the extension wire, such that saidproximal end of the guidewire or the distal end of the extension wire isextendible partly through the lumen of the first polymeric sleeve, saidsecond sleeve end being attachable concentrically to the other of theproximal end of the guidewire or the distal end of the extension wire,said lumen having a diameter that expands radially when the sleeve isunder axial compression during introduction of the proximal end of theguidewire or the distal end of the extension wire and contracts radiallywhen the sleeve is under axial tension.
 2. The guidewire of claim 1additionally comprising a second polymeric sleeve having first andsecond ends and a lumen extending therebetween, said first end having asmaller inside diameter than said second end, said first end beingconcentric about the first polymeric sleeve, said second end beingadapted to receive the proximal end of the guidewire, and to guide theguidewire into the proximal end of the first polymeric sleeve.
 3. Theextendable guidewire assembly of claim 1 wherein the first polymericsleeve is fixedly attached about the distal end of the extension wire.4. The extendable guidewire assembly of claim 1 wherein the taper of theproximal end of the guidewire is a conical taper and the taper of thedistal end of the extension wire is a conical taper.
 5. The extendableguidewire assembly of claim 1 wherein said one end to which the sleeveis fixedly attached extends through greater than half the length of thesleeve lumen.
 6. The extendable guidewire assembly of claim 1 whereinthe untapered diameter of the guidewire is about 0.3 to 0.4 mm, theuntapered diameter of the extension wire is about 0.3 to 0.4 mm, and thediameter of the sleeve lumen is less than said untapered diameter of theguidewire.
 7. The extendable guidewire assembly of claim 6 wherein thelength of the tapered end of the guidewire is 3 to 7 cm, the length ofthe tapered end of the extension wire is 3 to 7 cm.
 8. The extendableguidewire assembly of claim 7 wherein the sleeve has a wall thickness of0.025 to 0.05 mm.
 9. The extendable guidewire assembly of claim 1wherein the polymer is polyimide and the helical coil is formed of metalribbon.
 10. The extendable guidewire assembly of claim 1 wherein thepolymer is polyimide and the helical coil is formed of metal wire.